Field of the Invention
The invention concerns a crosshead bearing, in particular for stroke piston machines, including a bearing surface that contains multiple oilways running axially, each of which is connected through a rearward borehole to a lubricant supply.
Background of the Art
A stroke piston device 10 is shown in FIG. 4 that has a crosshead bearing 12 and a lubricant supply 14. When the crosshead bearing is constructed, regardless of the expected operating conditions, there must be an oil source between the crosshead bearing and the pivot connected to it. Because a crosshead bearing has no rotational motion at the bearing, there is no appreciable fresh oil transport generated by rotary motion. Oil pushed out by the radial motion on the loaded side of the bearing must be replaced with fresh oil during the next movement of the pivot on the opposite side of the bearing, because only limited lateral replenishment is possible due to the quick motion of the pivot, so the oil vapor pressure is reduced and the result is an inadequate supply of oil to this area. This area of the bearing must be constructed so that it refills until the next load stroke.
Usually, in particular in compressor construction, oilways distributed in a circumferential direction are installed on the bearing surface and supplied with pressurized oil from the back of the bearing. Under the assumption that oil transport outward from each of the oilways in the loaded bearing surface is made possible essentially by the swinging motion of the crosshead bearing, the distance between oilways is generally based on the size of the swing angle, i.e., for example, a distance of 15° from each other. For this reason, there is no oilway in the bearing's force direction, because the roughly parabolic pressure build-up in the opposing central load positions should not be interrupted by an oilway. A crosshead bearing of this type is described in DE 35 19 984 A1.
DE 27 11 983 A1 discloses bearing seats with one or more oilways arranged circumferentially within an angle range of 60° to 150°. The sum of the lengths of the ranges that appear in any cross section with axial direction should be 5 to 50% of the bearing seat width, such that a predominantly dense structure of oilways is created. The predominantly transversally-running oilways in known art structures of this type are distributed arbitrarily and always placed outside of the areas where the highest pressure is expected.
AT 007 501 U1 discloses a crosshead bearing with just one oilway placed outside of the central load positions. Experts in this field are of the opinion that it is disadvantageous to design known art crosshead bearings with just one oilway in the highest load zone, because the force applied by the connecting rod to the gudgeon pin is always in the direction of the connecting rod axis. The surface pressure in this area of a central load position would be increased by the oilway.
The fundamental disadvantage of known art crosshead bearings lies in the fact that both of the bearing surfaces located in the area of the central load positions are essentially linked to the hydrodynamic pressure build-up. However many oilways there are, they are outside of these areas. The bearing surfaces located farther away from the load positions build up only low pressure, because the displacement mechanism there has a significantly weaker effect due to the wider lubrication opening in that area. The peak oil pressure is relatively high in the central load position areas.